Primer aligner stages for lag issue resolution in low-stage clear aligner treatments

ABSTRACT

A set of primer appliances and a set of treatment appliances to be worn by a subject are provided. The primer appliances are first worn to prepare the local environment of the teeth for further repositioning of the teeth by the treatment appliances. The primer appliances may apply compression to the periodontal ligament, in a direction favorable for achieving the desired final position of a tooth. The compression may generate a biological response in the local environment of the teeth. The primer appliances may cause minimal or no repositioning of the teeth. The treatment appliances are worn to reposition the teeth from an initial position to an end position of a treatment stage. The primer appliances can improve the efficiency and accuracy of tooth movement by the treatment appliances.

CROSS-REFERENCE

This application claims the benefit of U.S. Provisional Application No.62/119,728, filed Feb. 23, 2015, the disclosure of which is incorporatedherein by reference in its entirety.

BACKGROUND

Prior methods and apparatus for aligning teeth can be less than ideal inat least some instances. While braces can be used to move teeth intoalignment, braces can be cumbersome to wear and can require expertise toplace on the subject. Also, complex movements can be difficult toachieve and orthodontic placement may less than ideally address thecomplex movements of several teeth in at least some instances.

Transparent shell appliances have been used to successfully move teeth.For example, a user can be provided with a series of transparent shellappliances. Each shell of the series of shells may correspond to a stageof the treatment. For example, a fourth shell in a series of ten shellsmay correspond to the fourth state of treatment. Although transparentshell appliances can be used to successfully reposition teeth, thetransparent shell appliances can provide less than ideal results in atleast some instances. For example, complex movements of teeth, such asto fill an extraction can be difficult to treat with transparent shellappliances. Also, in at least some instances, a wearer of a transparentshell appliance may not complete treatment, for example when teeth donot move sufficiently with the appliances and the user stops treatment.And, in at least some instances, the course of treatment may need to bereevaluated as the treatment is implemented, which may necessitate themanufacture of a second series of transparent shell appliances,prolonging treatment time.

In light of the above, it would be desirable to provide improved methodsand apparatus for moving teeth to target positions with polymeric shellappliances. Ideally, such methods and apparatus would more accuratelymove teeth to target positions with improved biological response and agreater likelihood of completing treatment.

SUMMARY

Embodiments of the present disclosure provide a system for repositioningteeth comprising a set of primer appliances to be worn by the subjectand a set of treatment appliances. The primer appliances can be providedto a subject as an initial, primer stage of the repositioning treatment,to prepare the local environment of the subject's teeth for furtherrepositioning of the teeth by the treatment appliances during thetreatment stage. The primer appliances may apply gentle force withstrain to the periodontal ligament with one or more of compression,stretching or elongation to the periodontal ligament. The force withstrain may be applied in one or more of many directions. The directionof the gentle force with strain to the periodontal ligament can beapplied in the direction of desired movement of the teeth, which maycorrespond to the desired final position of the teeth, or away from thedirection of desired tooth movement, such as outwardly. The gentle forcewith strain to the periodontal ligament can generate a biologicalresponse in the local environment of the teeth, including the productionof one or more biochemical signals that may be related to the process ofremodeling of oral tissue and bone. The gentle force with strain appliedby the primer appliances may cause little or no repositioning of theteeth. Alternatively, the gentle force with strain applied by the primerappliances may reposition the teeth at a slower rate than the treatmentappliances. The primer stage may be placed on the teeth for an initialtreatment stage sufficient for achieving a desired biological responsein the subject. The initial treatment stage can be for length of timewithin a range from about 3 weeks to about 8 weeks. Subsequent to theprimer stage, treatment appliances may be provided to the subject toreposition the teeth. The treatment appliances may comprise one or moresets of treatment appliances, corresponding to one or more stages oftreatment. The treatment appliances can be worn to reposition the teethfrom an initial position to an end positon of a treatment stage. Througha plurality of treatment stages, a plurality of treatment appliances canbe progressively worn and replaced so that the teeth are eventuallyrepositioned by the set of treatment appliances to desired endpositions. Priming the teeth for repositioning using the primerappliances can reduce the length of time for which each set of treatmentappliances is worn by the subject, reduce the total length of time ofthe treatment, increase the total amount of possible tooth movement,decrease unwanted tooth movement, and improve the predictability andaccuracy of tooth movement, hence allowing more subjects to successfullycomplete treatment.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIG. 1 illustrates a jaw together with an incremental positioningadjustment appliance according to embodiments of the present disclosure;

FIG. 2 is a flowchart of a process of specifying a course of treatmentaccording to embodiments of the present disclosure;

FIG. 3 is a schematic of a treatment course for moving and repositioningteeth according to embodiments of the present disclosure; and

FIG. 4 shows a graph of tooth position over the course of a treatmentaccording to embodiments of the present disclosure.

DETAILED DESCRIPTION

The present disclosure provides improved and more effective orthodonticsystems and related methods for moving teeth to elicit a desired toothmovement and/or repositioning teeth into a desired arrangement. Themethods and apparatus disclosed herein can be combined in many ways andused to treat one or more of many teeth conditions.

In some embodiments, certain methods and apparatus of aligning teethwith transparent shell appliances can rely on providing transparentshell appliances which may be worn progressively at substantiallysimilar time intervals and which each may provide a rate of teethmovement that is substantially the same at each treatment stage. Work inrelation to embodiments suggests that such an approach may provide lessthan ideal results in at least some instances as the biological responseto wearing the shell appliances may not be consistent throughout thecourse of a treatment. For example, the teeth may be more resistant torepositioning in the first few stages of a treatment and as a result,the teeth may not be in the desired or planned position when these earlystages are supposed to be completed. In at least some cases, this lag ordiscrepancy in treatment may prolong the total time required fortreatment as the subject may opt to wear the early stage shellappliances for a longer period. In at least some cases, the lag ordiscrepancy may even necessitate a reevaluation of the treatment stagesso that the treatment can begin anew at the present position of theteeth after the early treatment stages rather than the planned position.In some cases, a subject may decide not to complete treatment.

Work in relation to the present disclosure suggests that the sometreatment planning and force systems with polymeric shell appliances maynot take into consideration lag of tooth position with respect to anintended position. Work in relation to embodiments also suggests that insome embodiments, the sequential positions of tooth positioningappliances may less than ideally address a higher resistance to movementof the teeth during the first few stages of appliance treatment. Thishigher resistance of the first few stages may be related to tissueelasticity, and the time allocated for biological response with theprior tooth positioning appliances may not be sufficient.

In one aspect, a method of repositioning teeth of a subject is provided.The method can comprise providing one or more primer appliances to beplaced on a plurality of teeth of the subject to prepare supportstructures of the plurality of the teeth for repositioning, wherein theone or more primer appliances comprises a plurality of tooth receivingcavities shaped to provide an amount of force or torque to the pluralityof teeth sufficient to induce a biological response of the supportstructures.

In many embodiments, the plurality of tooth receiving cavities is shapedto provide the amount of force or torque to the plurality of teethwithout permanently moving the plurality of the teeth when thebiological response has been induced and the plurality of teeth areready for repositioning.

In many embodiments, the one or more primer appliances are providedduring an intermediate portion of treatment before a movement phase ofthe plurality of teeth.

In many embodiments, the one or more primer appliances are provided foruse after previous treatment comprising one or more of palatal expansionor mandibular repositioning and functional appliances configured to movethe plurality of teeth are provided for use before the one or moreprimer appliances.

In many embodiments, the one or more primer appliances are provided foruse after previous treatment comprising one or more of palatal expansionor mandibular repositioning and wherein functional appliances configuredto move the plurality of teeth are provided for use after the one ormore primer appliances.

In many embodiments, the method further comprises: providing a pluralityof appliances of an intermediate portion of treatment, the intermediateportion of the treatment comprising a plurality of repositioning stagesof treatment. The method can further comprise providing one or morefinishing appliances for use in a finishing stage of treatment. Theintermediate portion of treatment can comprise providing a plurality ofrepositioning appliances of a plurality of repositioning stages in orderto incrementally move the plurality of teeth toward final positions andone or more of the plurality of teeth can move between adjacentrepositioning stages with a repositioning distance per unit time greaterthan a distance moved per unit time during a primer stage. In manyembodiments, a plurality of positions of the plurality of toothreceiving cavities of the one or more finishing appliances comprises aplurality of final positions of the plurality of tooth receivingcavities corresponding to a plurality of final positions of theplurality of teeth.

In many embodiments, the one or more primer appliances are placed on theplurality of teeth for a time sufficient to induce the biologicalresponse of the support structures, the sufficient time comprising atleast about two weeks.

In many embodiments, the one or more primer appliances are placed on theplurality of teeth for a time sufficient to induce the biologicalresponse of the support structures, the time within a range from aboutthree weeks to about twelve weeks.

In many embodiments, the subject is an adult of age 18 or more years oldand the one or more primer appliances are placed on the plurality ofteeth for a time sufficient to induce the biological response of thesupport structures, the time within a range from about three weeks toabout twelve weeks.

In many embodiments, an amount of movement of the plurality of teethupon completion of a primer portion of treatment with the one or moreprimer appliances is not sufficient to have permanently moved theplurality of teeth more than about half a distance from initialpositions of the plurality of teeth prior to placement of the one ormore primer appliances to positions of the plurality of tooth receivingcavities of the one or more primer appliances.

In many embodiments, each of the plurality of tooth receiving cavitiesis shaped to position a received tooth to provide the amount of force ortorque to the plurality of the teeth without permanently moving theplurality of teeth when the biological response has been induced and theteeth are ready for repositioning.

In many embodiments, one or more of the plurality of tooth receivingcavities is shaped to displace one or more of the plurality of teeth ina pre-conditioning direction of the one or more primer appliances, thepre-conditioning direction away from a repositioning direction of aninitial repositioning stage in order to facilitate movement in therepositioning direction with the initial repositioning stage.

In many embodiments, the one or more primer appliances are configured tomove the plurality of teeth from a plurality of first positions to aplurality of second positions over a first amount of time, such movementfrom the plurality of first positions to the plurality of secondpositions corresponding to a first rate of movement. The method canfurther comprise: providing a plurality of repositioning appliances ofrepositioning stages of treatment to reposition the plurality of teethwith a second rate of movement greater than the first rate of movement.

In many embodiments, the one or more primer appliances are configured toapply a controlled distribution of strain on a periodontal ligament ofeach tooth of the plurality of teeth received by the plurality of toothreceiving cavities of the one or more primer orthodontic appliances.

In many embodiments, the one or more primer appliances lower resistanceof a tissue of the subject to the repositioning of the plurality ofteeth with the repositioning appliances. The tissue can comprise aperiodontal ligament.

In many embodiments, the one or more primer appliances produce abiological response in a local environment of the plurality of teeth.The biological response can comprise bone remodeling. The biologicalresponse can comprise one or more of a change in a concentration of abiochemical signal or a change in a cellular makeup of the localenvironment.

In many embodiments, the method further comprises: placing the one ormore primer appliances on the plurality of teeth; and placing one ormore repositioning appliances on the plurality of teeth, wherein the oneor more primer appliances are placed prior to the one or morerepositioning appliances so as to reduce distortion of the one or morerepositioning appliances when placed on the plurality of teeth.

In another aspect, a system for repositioning teeth of a subject isprovided. The system can comprise one or more primer appliances to beplaced on a plurality of teeth of the subject to prepare supportstructures of the plurality of teeth for repositioning, wherein the oneor more primer appliances comprises a plurality of tooth receivingcavities shaped to provide an amount of force or torque to the pluralityof teeth sufficient to induce a biological response of the supportstructures.

In many embodiments, the plurality of tooth receiving cavities is shapedto provide the amount of force or torque to the plurality of teethwithout permanently moving the plurality of teeth when the biologicalresponse has been induced and the plurality of teeth are ready forrepositioning.

In many embodiments, the system further comprises a plurality ofappliances for an intermediate portion of treatment, the intermediateportion of the treatment comprising a plurality of repositioning stagesof treatment. The system can further comprise one or more finishingappliances for use in a finishing stage of treatment.

In many embodiments, the plurality of appliances for the intermediateportion of treatment comprises a plurality of repositioning appliancesof a plurality of corresponding repositioning stages in order toincrementally move the plurality of teeth toward final positions andwherein the plurality of repositioning appliances is configured to moveone or more of the plurality of teeth between adjacent repositioningstages with a repositioning distance per unit time greater than adistance moved per unit time during a primer stage.

In many embodiments, a plurality of positions of the plurality of toothreceiving cavities of the one or more finishing appliances comprises aplurality of final positions of the plurality of tooth receivingcavities corresponding to a plurality of final positions of theplurality of teeth.

In many embodiments, the one or more primer appliances are configured tobe placed on the plurality of teeth for a time sufficient to induce thebiological response of the support structures, the time within a rangefrom about three weeks to about twelve weeks.

In many embodiments, the one or more primer appliances are configuredsuch that an amount of movement of the plurality of teeth uponcompletion of a primer portion of treatment with the one or more primerappliances is not sufficient to have permanently moved the plurality ofteeth more than about half a distance from initial positions of theplurality of teeth prior to placement of the one or more primerappliances to positions of the plurality of tooth receiving cavities ofthe one or more primer appliances.

In many embodiments, each of the plurality of tooth receiving cavitiesis shaped to position a received tooth to provide the amount of force ortorque to the plurality of the teeth without permanently moving theplurality of teeth when the biological response has been induced and theteeth are ready for repositioning.

In many embodiments, one or more of the plurality of tooth receivingcavities is shaped to displace one or more of the plurality of teeth ina pre-conditioning direction of the one or more primer appliances, thepre-conditioning direction away from a repositioning direction of aninitial repositioning stage in order to facilitate movement in therepositioning direction with the initial repositioning stage.

In many embodiments, the one or more primer appliances are configured tomove the plurality of teeth from a plurality of first positions to aplurality of second positions over a first amount of time, such movementfrom the plurality of first positions to the plurality of secondpositions corresponds to a first rate of movement, wherein a pluralityof repositioning appliances of corresponding repositioning stages oftreatment is configured to reposition the plurality of teeth with asecond rate of movement greater than the first rate of movement.

In many embodiments, the one or more primer appliances are configured toapply a controlled distribution of strain on a periodontal ligament ofeach tooth of a plurality of teeth received by tooth receiving cavitiesof the one or more primer orthodontic appliances.

In many embodiments, the one or more primer appliances lower resistanceof a tissue of the subject to the repositioning of the plurality ofteeth with the repositioning appliances. The tissue can comprise aperiodontal ligament.

In many embodiments, the one or more primer appliances produce abiological response in a local environment of the plurality of teeth.The biological response can comprise bone remodeling. The biologicalresponse can comprise one or more of a change in a concentration of abiochemical signal or a change in a cellular makeup of the localenvironment.

In another aspect, a system is provided comprising a processorcomprising instructions to generate one or more primer appliances inresponse to user input and instructions to output data to manufacturethe one or more primer appliances.

In another aspect, a method of planning an orthodontic treatment isprovided. The method can comprise: receiving an initial digital data setrepresenting an initial arrangement of a patient's teeth; generating aplurality of intermediate arrangements for successively repositioningthe patient's teeth from the initial arrangement towards a targetarrangement; determining geometries for one or more primer appliancescomprising teeth receiving cavities shaped to prepare the patient'steeth for the repositioning from the initial arrangement towards thetarget arrangement, wherein the teeth receiving cavities of the one ormore primer appliances are each shaped according to a first intermediatearrangement of the plurality of intermediate arrangements; anddetermining geometries for a plurality of treatment appliancescomprising teeth receiving cavities shaped to successively repositionthe patient's teeth from the initial arrangement towards the targetarrangement, wherein the teeth receiving cavities of the plurality oftreatment appliances are each shaped according to a respectiveintermediate arrangement of the plurality of intermediate arrangementsfollowing the first intermediate arrangement.

In many embodiments, the teeth receiving cavities of the one or moreprimer appliances are each shaped to move the patient's teeth at a firstmovement rate, and the teeth receiving cavities of the plurality oftreatment appliances are each shaped to move the patient's teeth at asecond movement rate, the second movement rate being greater than thefirst movement rate.

In many embodiments, the teeth receiving cavities of the one or moreprimer appliances are each shaped to move the patient's teeth by a firstmovement amount, and the teeth receiving cavities of the plurality oftreatment appliances are each shaped to move the patient's teeth by asecond movement amount, the second movement amount being greater thanthe first movement amount.

In many embodiments, the teeth receiving cavities of the one or moreprimer appliances are each shaped to apply force and/or torque to thepatient's teeth without moving the patient's teeth, and the teethreceiving cavities of the plurality of treatment appliances are eachshaped to apply force and/or torque to the patient's teeth that elicitmovement of the patient's teeth.

In many embodiments, the one or more primer appliances comprise aplurality of primer appliances having the same teeth receiving cavitygeometries. As used herein, “same teeth receiving cavity geometries” maymean that the teeth receiving cavities have the same size, shape,position, and/or orientation. For instance, teeth receiving cavitieswith the same geometry can have the same position and orientationrelative to the patient's arch when the appliance is worn by thepatient. The plurality of primer appliances can comprise three or moreprimer appliances having the same teeth receiving cavity geometries. Theplurality of treatment appliances can each have different teethreceiving cavity geometries.

In many embodiments, the method further comprises generatinginstructions for fabricating the one or more primer appliances and theplurality of treatment appliances. The method can further comprisefabricating the one or more primer appliances and the plurality oftreatment appliances based on the generated instructions.

In many embodiments, the teeth receiving cavities of the one or moreprimer appliances are each shaped to prepare the patient's teeth for therepositioning by lowering resistance of a tissue of the patient to therepositioning of the teeth. Lowering the resistance can comprise one ormore of: initiating bone remodeling, initiating a change in one or moreproperties of a periodontal ligament, initiating a change inconcentration of a biochemical signal, or initiating a change in acellular makeup of a local environment of the teeth. The teeth receivingcavities of the plurality of treatment appliances can each be shaped tosuccessively reposition the patient's teeth from the initial arrangementtowards the target arrangement after the resistance of the tissue hasalready been lowered by the one or more primer appliances.

In another aspect, a method of planning an orthodontic treatment isprovided. The method can comprise: determining a plurality of teeth tobe repositioned from a first arrangement to a second arrangement duringthe orthodontic treatment; identifying a first subset of the pluralityof teeth that have already been repositioned in a previous stage of theorthodontic treatment; identifying a second subset of the plurality ofteeth that have not yet been repositioned in a previous stage of theorthodontic treatment; and determining a first movement rate for thefirst subset of the plurality of teeth and a second movement rate forthe second subset of the plurality of teeth, wherein the first movementrate is greater than the second movement rate.

In many embodiments, the second movement rate is configured to preparethe second subset of the plurality of teeth for repositioning. Thesecond movement rate can be configured to prepare the second subset ofthe plurality of teeth for repositioning by lowering resistance of atissue of the patient to the repositioning of the plurality of teeth.Lowering the resistance can comprise one or more of: initiating boneremodeling, initiating a change in one or more properties of aperiodontal ligament, initiating a change in concentration of abiochemical signal, or initiating a change in a cellular makeup of alocal environment of the teeth.

In many embodiments, the method further comprises determining geometriesfor a plurality of appliances shaped to successively reposition theplurality of teeth from the first arrangement to the second arrangement.The plurality of appliances can each comprise a first set of toothreceiving cavities shaped to reposition the first subset of theplurality of teeth according to the first movement rate and a second setof tooth receiving cavities shaped to reposition the second subset ofthe plurality of teeth according to the second movement rate. In otherwords, a single appliance may have some tooth receiving cavities thatare intended to reposition teeth and some tooth receiving cavities thatare intended to prime teeth for repositioning. The second sets of toothreceiving cavities of the plurality of appliances can each comprise thesame cavity geometries. The first sets of tooth receiving cavities ofthe plurality of appliances can each comprise different cavitygeometries. The plurality of appliances can comprise three or moreappliances. The method can further comprise generating instructions forfabricating the plurality of appliances and/or fabricating the pluralityof appliances based on the generated instructions. The plurality ofappliances can each be configured to be worn by a patient for the sameamount of time.

In another aspect, a method of planning an orthodontic treatment isprovided. The method can comprise: receiving an initial digital data setrepresenting an initial arrangement of a patient's teeth; generating aplurality of intermediate arrangements for successively repositioningthe patient's teeth from the initial arrangement towards a targetarrangement; determining a first time period for repositioning thepatient's teeth from the initial arrangement to a first intermediatearrangement of the plurality of intermediate arrangements; anddetermining a second time period for repositioning the patient's teethfrom the first intermediate arrangement to a second, subsequentintermediate arrangement of the plurality of intermediate arrangement,wherein the first time period is longer than the second time period.

In many embodiments, the first time period is sufficiently long toprepare the teeth for repositioning.

In many embodiments, the first time period is sufficiently long to lowerresistance of a tissue to the repositioning of the teeth. Lowering theresistance can comprise one or more of: initiating bone remodeling,initiating a change in one or more properties of a periodontal ligament,initiating a change in concentration of a biochemical signal, orinitiating a change in a cellular makeup of a local environment of theteeth.

In many embodiments, the first time period is greater than or equal toabout two weeks.

In many embodiments, the first time period is within a range from abouttwo weeks to about twelve weeks.

In many embodiments, the first time period is at least three timeslonger than the second time period.

In many embodiments, a movement distance of the teeth from the initialarrangement to the first intermediate arrangement is the same as amovement distance of the teeth from the first intermediate arrangementto the second intermediate arrangement.

In many embodiments, the second intermediate arrangement is immediatelysubsequent to the first intermediate arrangement.

In many embodiments, the method further comprises determining a thirdtime period for repositioning the patient's teeth from the secondintermediate arrangement to a third, subsequent intermediate arrangementof the plurality of intermediate arrangement, wherein the third timeperiod is equal to the second time period.

In many embodiments, the method further comprises determining geometriesfor a plurality of appliances shaped to successively reposition theplurality of teeth from the initial towards the target arrangement,wherein the plurality of appliances comprises a plurality of primerappliances shaped to reposition the patient's teeth from the initialarrangement to the first intermediate arrangement over the first timeperiod and a plurality of treatment appliances shaped to reposition thepatient's teeth from the first intermediate arrangement to the secondintermediate arrangement over the second time period. The plurality ofappliances can each be configured to be worn by the patient for the sameamount of time. The plurality of primer appliances can comprise three ormore primer appliances.

In another aspect, a system for planning an orthodontic treatment isprovided. The system can comprise one or more processors configured toperform a method according to any of the embodiments herein.

As used herein and/or is a grammatical conjunction indicating that oneor more of the elements connected with this grammatical conjunction maybe provided. For example, A and/or B indicates one or more of A alone,or B alone, and combinations of A and B.

As used herein a “plurality of teeth” encompasses two or more teeth.

As used herein a primer stage encompasses an initial stage of treatmentto condition support structures of teeth for movement.

As used herein a repositioning stage encompasses an intermediate stageof treatment in which one or more teeth is repositioned toward anintended final position upon completion of treatment.

As used herein a finishing stage of treatment encompasses a final stageof treatment in which one or more teeth positioning appliances havingtooth receiving cavities shaped to move teeth to final positions isplaced on the teeth.

The methods and apparatus provided herein can take into considerationthe natural lag in response of a tooth during the early phase of toothrepositioning treatment. In many instances, during the first few stagesof repositioning treatment, the tooth can exhibit a higher resistance toaccomplishing movement. The higher resistance to movement may be due tothe relatively high elasticity of the periodontal ligaments during theearly stages of repositioning treatment. Alternatively or incombination, the higher resistance to movement may be due to the timerequired for the initiation of a biological response in the localenvironment of the tooth, the biological response enabling toothmovement in response to forces applied by appliances such as polymericshell appliances. The biological response may comprise, for example,changes in concentrations of biochemical signals (e.g., cytokines,enzymes, growth factors, hormones, etc.) in the tissue or in thegingival crevicular fluid, or changes in the cellular makeup of thelocal environment (e.g., recruitment of cells, differentiation ofcells). The biological response may be affected by cells within oraround the periodontal ligament, such as osteocytes, osteoclasts,osteoblasts, fibroblasts, or circulating progenitor cells. Pre-loadingone or more teeth with one or more primer aligners or appliances asdescribed herein can provide sufficient time for changes in one or moreproperties of the periodontal ligaments, and thus lower the resistanceto tooth movement. Further, the primer appliances can help produceand/or expedite the biological response involved in bone remodeling.Thus, the primer stage can provide easier and more predictable movementsof the teeth during the subsequent treatment stage. After the primerstage, the treatment appliances may can be configured to move the teethwith greater incremental amounts.

Appliances having teeth receiving cavities that receive and repositionteeth, e.g., via application of force due to appliance resiliency, aregenerally illustrated with regard to FIG. 1. As illustrated, FIG. 1shows one exemplary adjustment appliance 11 which is worn by the patientin order to achieve an incremental repositioning of individual teeth inthe jaw 10. The appliance can include a shell (e.g., polymeric shell)having teeth-receiving cavities that receive and resiliently repositionthe teeth. Similar appliances, including those utilized in theInvisalign® System, are described in numerous patents and patentapplications assigned to Align Technology, Inc. including, for examplein U.S. Pat. Nos. 6,450,807, and 5,975,893, as well as on the company'swebsite, which is accessible on the World Wide Web (see, e.g., the URL“align.com”).

As set forth in the prior applications, an appliance can be designedand/or provided as part of a set or plurality of appliances andtreatment can be administered according to a treatment plan. In suchembodiments, each appliance may be configured so that one or moretooth-receiving cavities have a geometry corresponding to anintermediate or final tooth arrangement intended for the appliance.Appliance geometries can be further designed or modified (e.g., modifiedto accommodate or operate in conjunction with tooth attachments) so asto apply a desired force or system of forces to the patient's teeth andelicit a desired tooth movement and gradually reposition teeth to anintended arrangement. The patient's teeth can be progressivelyrepositioned from their initial tooth arrangement to a final tootharrangement by placing a series of incremental position adjustmentappliances over the patient's teeth. The adjustment appliances can begenerated all at the same stage or in sets or batches, e.g., at thebeginning of a stage of the treatment, and the patient wears eachappliance until the pressure of each appliance on the teeth can nolonger be felt. A plurality of different appliances (e.g., set) can bedesigned and even fabricated prior to the patient wearing any applianceof the plurality. At that point, the patient can replace the currentadjustment appliance with the next adjustment appliance in the seriesuntil no more appliances remain. The appliances may be not affixed tothe teeth and the patient may place and replace the appliances at anytime during the procedure. The final appliance or several appliances inthe series may have a geometry or geometries selected to overcorrect thetooth arrangement, i.e., have a geometry which can (if fully achieved)move individual teeth beyond the tooth arrangement which has beenselected as the “final.” Such over-correction may be desirable in orderto offset potential relapse after the repositioning method has beenterminated, i.e., to permit movement of individual teeth back towardtheir pre-corrected positions. Over-correction may also be beneficial tospeed the rate of correction, i.e., by having an appliance with ageometry that is positioned beyond a desired intermediate or finalposition, the individual teeth will be shifted toward the position at agreater rate. In such cases, the use of an appliance can be terminatedbefore the teeth reach the positions defined by the appliance.

Orthodontic appliances, such as illustrated in FIG. 1, can impart forcesto the crown of a tooth and/or an attachment positioned on the tooth ateach point of contact between a tooth receiving cavity of the applianceand received tooth and/or attachment. The magnitude of each of theseforces and their distribution on the surface of the tooth may determinethe type of orthodontic tooth movement which results. Types of toothmovements can be conventionally delineated as extrusion, intrusion,rotation, tipping, translation and root movement. Tooth movement of thecrown greater than the movement of the root can be referred to astipping. Equivalent movement of the crown and root can be referred to astranslation. Movement of the root greater than the crown can be referredto as root movement.

As described above, a patient's teeth can be generally progressivelyrepositioned according to a treatment plan. Exemplary methods fortreatment plan design, as well as appliance design and fabrication aredescribed further below. Typically, appliance and/or treatment plandesign can optionally, though not necessarily, be accomplished usingvarious computer based applications. It will be recognized thatappliance design and fabrication is not limited to any particular methodand can include various computer and non-computer based methodologies.

Treatment planning, according to embodiments of the present disclosure,is described. Patient data can be collected and analyzed, and specifictreatment steps specified and/or prescribed. In many embodiments, atreatment plan can be generated and proposed for a dental practitionerto review. The dental practitioner can accept or request modificationsto the treatment plan. Once the treatment plan is approved,manufacturing of appliance(s) can begin. Digital treatment plans can begenerated with 3-dimensional orthodontic treatment planning tools suchas software provided by Align Technology, Inc. or other softwareavailable from eModels and OrthoCAD, among others. These technologiescan allow the clinician to use the actual patient's dentition as astarting point for customizing the treatment plan. The softwaretechnology of Align Technology, Inc., may use a patient-specific digitalmodel to plot a treatment plan, and then uses a scan of the achieved oractual treatment outcome to assess the degree of success of the outcomeas compared to the original digital treatment plan as discussed in U.S.patent application Ser. No. 10/640,439, filed Aug. 12, 2003, now U.S.Pat. No. 7,156,661, issued Jan. 2, 2007, and U.S. patent applicationSer. No. 10/225,889 filed Aug. 22, 2002, now U.S. Pat. No. 7,077,647,issued Jul. 18, 2006.

Examples of polymeric shell appliances suitable for incorporation inaccordance with embodiments of the present disclosure suitable aredescribed in U.S. application Ser. No. 12/623,340, filed on Nov. 20,2009, published as US 2010/0138025 on Jun. 3, 2010, entitled“Orthodontic systems and methods including parametric attachments,” andU.S. application Ser. No. 13/865,091, filed on Apr. 17, 2013, publishedas US 2013/0230818, entitled “Method and system for optimizing dentalaligner geometry,” the entire disclosures of which are incorporatedherein by reference.

In many instances and for many movements, a plain polymeric shellappliance may work well. Features can be added when there are difficultmovements such as significant rotation, extrusion, or root movement.Even so, the plain polymeric shell appliance itself can still create themajority of force and moment to move the tooth. The primer appliances asdescribed herein may have structures such as power ridges to enhancetooth movement, and can be shaped to receive features such asattachments placed on the teeth. Alternatively, the primer appliances asdescribed herein may not have structures such as power ridges and maynot be shaped to receive features such as attachments placed on theteeth.

A manufacturing process for a plain polymeric shell appliance may be asfollows. First, initial and final teeth positions may be acquired and amovement path may be generated of all the teeth. Then, additionalfeatures such as attachments, dimples, and ridges may be added to theteeth. A 3D printer may then be used to print the physical mold of theteeth, jaw, and other features. A thin plastic sheet may be thermalformed on the mold. The gingival line may be cut and the polymeric shellappliance may be removed from the mold. Finally, the plain polymericshell appliance may be cleaned and packaged.

The appliance as described herein can be formed in one or more of manyways and may comprise a machined piece of material, a thermoformedmaterial, a 3D printed material, and combinations thereof, for example.

Although reference is made to an appliance comprising a polymeric shellappliance, the embodiments disclosed herein are well suited for use withmany appliances that receive teeth, for example appliances without oneor more of polymers or shells. The appliance can be fabricated with oneor more of many materials such as metal, glass, reinforced fibers,carbon fiber, composites, reinforced composites, aluminum, biologicalmaterials, and combinations thereof for example. The appliance can beshaped in many ways, such as with thermoforming or direct fabrication asdescribed herein, for example. Alternatively or in combination, theappliance can be fabricated with machining such as an appliancefabricated from a block of material with computer numeric controlmachining.

FIG. 2 illustrates the general flow of an exemplary process 100 forgenerating a treatment plan or defining and generating repositioningappliances for orthodontic treatment of a patient. The process 100 canincorporate optimized and/or customized attachments and design thereofas described in U.S. patent application Ser. No. 12/623,340, filed Nov.20, 2009, now U.S. Pat. No. 9,161,823, issued Oct. 20, 2015, which isincorporated herein by reference. The process 100 may include themethods, and is suitable for optimized and/or customized attachments andapparatus, of the present disclosure, as will be described. Thecomputational steps of the process can be advantageously implemented ascomputer program modules for execution on one or more conventionaldigital computers.

As an initial step, a mold or a scan of patient's teeth or mouth tissueis acquired (step 110). This step 110 can involve taking casts of thepatient's teeth and gums, and may in addition or alternately involvetaking wax bites, direct contact scanning, x-ray imaging, tomographicimaging, sonographic imaging, and other techniques for obtaininginformation about the position and structure of the teeth, jaws, gumsand other orthodontically relevant tissue. From the data so obtained, adigital data set can be derived that represents the initial (that is,pretreatment) arrangement of the patient's teeth and other tissues.

The initial digital data set, which may include both raw data fromscanning operations and data representing surface models derived fromthe raw data, is processed to segment the tissue constituents from eachother (step 120). In particular, in this step 120, data structures thatdigitally represent individual tooth crowns can be produced.Advantageously, digital models of entire teeth can be are produced,including measured or extrapolated hidden surfaces and root structuresas well as surrounding bone and soft tissue.

The desired final position of the teeth—that is, the desired andintended end result of the orthodontic treatment or phase of orthodontictreatment—can be received from a clinician in the form of aprescription, can be calculated from basic orthodontic principles, orcan be extrapolated computationally from a clinical prescription (step130). With a specification of the desired final positions of the teethand a digital representation of the teeth themselves, the final positionand surface geometry of each tooth can be specified (step 140) to form acomplete model of the teeth at the desired end of treatment. Generally,in this step 140, the position of every tooth can be specified. Theresult of this step may be a set of digital data structures thatrepresents an orthodontically correct repositioning of the modeled teethrelative to presumed-stable tissue for the desired phase of orthodontictreatment. The teeth and tissue are both represented as digital data.

Having both a beginning position and a final position for each tooth,the process can next define a tooth path for the motion of each tooth(step 150). In some embodiments, the tooth paths can be optimized in theaggregate so that the teeth are moved in the quickest fashion with theleast amount of round-tripping to bring the teeth from their initialpositions to their desired final positions. Round-tripping can bedefined as any motion of a tooth in any direction other than directlytoward the desired final position. Round-tripping can sometimes benecessary to allow teeth to move past each other. The tooth paths can besegmented. The segments can be calculated so that each tooth's motionwithin a segment can stay within threshold limits of linear androtational translation. In this way, the end points of each profilesegment can constitute a clinically viable repositioning, and theaggregate of segment end points constitute a clinically viable sequenceof tooth positions, so that moving from one point to the next in thesequence does not result in a collision of teeth.

The threshold limits of linear and rotational translation areinitialized, in one implementation, with default values based on thenature of the appliance to be used. More individually tailored limitvalues can be calculated using patient-specific data. The limit valuescan also be updated based on the result of an appliance-calculation(step 170), which may determine that at one or more points along one ormore tooth paths, the forces that can be generated by the appliance onthe then-existing configuration of teeth and tissue is incapable ofeffecting the repositioning that is represented by one or more toothprofile segments. With this information, the sub-process definingsegmented paths (step 150) can recalculate the paths or the affectedsub-paths.

At various stages of the process, and in particular after the segmentedpaths have been defined, the process can, and generally will, interactwith a clinician responsible for the treatment of the patient (step160). Clinician interaction can be implemented using a client processprogrammed to receive tooth positions and models, as well as pathinformation from a server computer or process in which other steps ofprocess 100 are implemented. The client process can be advantageouslyprogrammed to allow the clinician to display an animation of thepositions and paths and to allow the clinician to reset the finalpositions of one or more of the teeth and to specify constraints to beapplied to the segmented paths. If the clinician makes any such changes,the sub-process of defining segmented paths (step 150) can be performedagain.

The segmented tooth paths and associated tooth position data can be usedto calculate clinically acceptable appliance configurations (orsuccessive changes in appliance configuration) that will move the teethon the defined treatment path in the steps specified by the profilesegments (step 170). Each appliance configuration may represent a stepalong the treatment path for the patient. The steps can be defined andcalculated so that each discrete position can follow straight-line toothmovement or simple rotation from the tooth positions achieved by thepreceding discrete step and so that the amount of repositioning requiredat each step involves an orthodontically optimal amount of force on thepatient's dentition. As with the path definition step, this appliancecalculation step can include interactions and even iterativeinteractions with the clinician (step 160). The operation of processsteps implementing this step 170 in a plurality of sub-steps isdescribed more fully in U.S. patent application Ser. No. 12/623,340,which is incorporated herein by reference.

Having calculated appliance definitions, the process 100 can proceed tothe manufacturing step (step 180) in which appliances defined by theprocess are manufactured, or electronic or printed information isproduced that can be used by a manual or automated process to defineappliance configurations or changes to appliance configurations.

With the set of orthodontic appliances manufactured, the timingparameters of the treatment can be adjusted to separate the set oforthodontic appliances into a set of primer orthodontic appliances and aset of treatment orthodontic appliances (step 190). Additionalorthodontic appliances may be manufactured depending on the needs of thepriming and treatment stages. For example, the set of primer orthodonticappliances may comprise a plurality of appliances corresponding to theprimer stage of treatment, which may be manufactured and worn as theprimer appliances.

In some subjects, the movement and repositioning of the teeth may not beas responsive to treatment in early stages of the treatment course. Forexample, in mature adults of ages 19 and older, teeth may not movesignificantly in the first 3 to 8 weeks of treatment, in contrast toyounger subjects whose teeth may experience movement within an hour ofthe beginning of treatment. The time lag between the initiation oftreatment and the movement of the teeth may be due to the time requiredfor the initiation of a biological response to the forces applied by theorthodontic appliances. For example, before bone remodeling can occur,the concentrations of many biochemical signals or messengers (e.g.,cytokines, growth factors, enzymes, hormones, etc.) in the localenvironment of the teeth may need to change, or the recruitment and/ordifferentiation of appropriate cell types may need to occur.Accordingly, accounting for the initial time lag in designing thetreatment stages can help ensure that the teeth of the subject movethrough the later stages of the treatment course with appropriate speedand accuracy. The primer orthodontic appliances may be worn to preparethe teeth and related anatomy, particularly the periodontal ligaments,for teeth movement and repositioning. The primer appliances may beconfigured to compress the periodontal ligament and the surroundingsupporting structure (e.g., gingiva, alveolar bone), in order to elicitthe appropriate biological response. After the primer orthodonticappliances have been worn for an appropriate length of time, thebiological response necessary for enabling bone remodeling andsubsequent movement of the teeth may be established, and the periodontalligaments may be less viscous, for example. In this manner, the laterworn treatment orthodontic appliances may accurately and effectivelymove and reposition the teeth. For example, fewer attachments to theteeth and/or less force may be applied to move and reposition teethwhich have been primed as such. Further, the primer appliances canimprove the predictability of tooth movement during the course oftreatment, reducing the need to adjust planned movement paths and/ormanufacture new treatment appliances to compensate for unpredictedmovements. In many embodiments, the increments for progressivelyreplacing the treatment orthodontic appliances may be decreased by usingprimer appliances. The primer appliances can thus shorten the length ofthe treatment as a whole.

Additionally, in some embodiments, application of treatment appliancesto a subject's teeth without first using one or more primer appliancesto prepare the teeth may result in distortion of the treatmentappliances. Distortion of treatment appliances may occur, for example,if the appliances are worn while the teeth are exhibiting higherresistance to movement and thus lag behind the planned movement for theappliances. For instance, if a first treatment appliance correspondingto a first treatment stage is worn, then a second treatment appliancecorresponding to a second treatment stage is worn even though the teethhave not progressed correspondingly, distortion (e.g., deformation,deflection, and/or warping) of the second treatment appliance may occur.Distortion may result in alteration of the contact points between theappliance and tooth and may reduce the effectiveness of the appliance inproducing the optimal force system for tooth movement. The extent ofdistortion may worsen as successive treatment appliances are placed,resulting in further deviations from the planned application of forcesand intended tooth movement trajectories. By using primer appliances toprepare the subject's teeth for movement, lag between the intended andachieved tooth movements during the treatment phase may be reduced oreliminated, and distortion of treatment appliances may be decreased.

In some embodiments, a primer appliance is shaped to move the teeth at alower movement rate compared to a treatment appliance. Alternatively orin combination, a primer appliance can be shaped to move the teeth by amovement amount less than that of a treatment appliance. A treatmentappliance may be designed to move teeth after resistance of the teethand/or intraoral tissues to movement has already been reduced by use ofprimer appliance. For instance, the amount and/or rate of movementachieved by a treatment appliance may be greater if the treatmentappliance is used after priming, and less if the treatment appliance isused without priming.

Although the above steps show the method 100 for generating a treatmentplan or defining and generating repositioning appliances for orthodontictreatment of a patient in accordance with many embodiments, a person ofordinary skill in the art will recognize many variations based on theteaching described herein. The steps may be completed in a differentorder. Steps may be added or deleted. Some of the steps may comprisesub-steps. Many of the steps may be repeated as often as beneficial tothe treatment.

One or more of the steps of the method 100 may be performed withcircuitry of a computing system as described herein, for example one ormore of a processor or logic circuitry of a computer or a computerizedsystem. The circuitry may be programmed to provide one or more of thesteps of the method 100, and the program may comprise programinstructions stored on a computer readable memory or programmed steps ofthe logic circuitry, for example.

In some embodiments, an orthodontic treatment plan can include multiplestages, such as a primer stage and a treatment stage. The primer stagemay be used to prepare teeth for movement (e.g., by lowering tissueresistance to repositioning), while the treatment stage may be used toactually effect the planned movement after application of the primerstage. In some embodiments, planning an orthodontic treatment involvesdetermining a plurality of intermediate tooth arrangements forrepositioning teeth from an initial arrangement towards a targetarrangement. A first time period for repositioning the patient's teethfrom the initial arrangement to a first intermediate arrangement can bedetermined, and this time period may correspond to the primer stage ofthe treatment. A second time period for repositioning the teeth from thefirst intermediate arrangement to a second intermediate arrangement canbe determined, and this time period may correspond to a first sub-stageof the treatment stage. Additional time periods can be determined forrepositioning the teeth to each subsequent intermediate arrangement,e.g., a third time period for repositioning teeth from the secondintermediate arrangement to a third intermediate arrangement, etc. Thefirst time period (the primer stage) may be longer than each of thesubsequent time periods (each treatment sub-stage) in order toadequately prepare the teeth for repositioning as described herein,e.g., at least three times longer. In some embodiments, the primer stageis longer than about two weeks, or within a range from about two weeksto about twelve weeks. The planned movement distance per tooth duringthe primer stage may be the same as the planned movement distance foreach treatment sub-stage, such that the teeth are intended to be movedat a slower rate during the primer stage than the treatment stage. Insome embodiments, lower movement rates during the primer stage areachieved by using multiple primer appliances having the same cavitygeometries (e.g., three or more primer appliances). The primerappliances may each be worn for the same period of time as the treatmentappliances (e.g., one to two weeks per appliance), such that providingmultiple primer appliances with the same geometries results in a lowerplanned movement rate compared to the treatment appliances.

FIG. 3 shows an exemplary schedule 300 having a primer stage 310 and atreatment stage 320. This figure shows primer aligners, treatmentaligners, finishing aligners, and retainers such as Vivera®, forexample. The primer stage 310 may comprise a first primer appliance 311,a second primer appliance 312, and a third primer appliance 313. Each ofthe primer appliances 311, 312, 313 may correspond to a first stage ofthe treatment course. Each of the primer appliances 311, 312, 313 may beworn for a first period of time, such as about 10 to 18 days, or such asabout two weeks. Alternatively, the primer stage 310 may comprise thesame primer appliance worn for the complete duration of the primerstage, for example about 3 to about 8 weeks. The configuration of theprimer appliances and/or the total duration of the primer stage may bedetermined based on one or more of age, race, ethnicity, tooth shape,and periodontal condition of the subject.

Although FIG. 3 makes reference to an exemplary schedule 300 inaccordance with an example of a method and a plurality of aligners asdescribed herein, the schedule 300 can be modified in many ways. Theprimer appliance can be applied somewhere in the middle of thetreatment. For example with segmental or with mandibular repositioningappliances, the primer stage can be provided after the mandibularrepositioning appliance, for example. The primer appliances can be usedwith one or more of many forms of tooth movement, such as alternativelyor in combination with minor tooth movement, for example. The primerappliance can be applied at one or more of prior to a difficult stage oftreatment, with a change in treatment plan, or a start of a new sectionof treatment, for example. The primer appliance concept as describedherein can be provided later in treatment; such as after mandibularadvancement, or palatal expansion, for example. The primer applianceconcept as described herein can be applied to the initiation of dentalmovement with one or more of many forms of dental treatment.

The first stage of the treatment course may or may not comprise a partof the programmed tooth movement path, such as a path defined in step150 of the method 100 described herein. In many embodiments, the firststage does not comprise the programmed path. In many embodiments, thefirst stage is configured to provide compression in a directionfavorable for achieving the desired final position of a tooth, such ascompression in a direction of intended tooth movement. The appropriateamount of compression to be provided to each tooth for achieving thedesired final position of the tooth may be determined using finiteelement analysis (FEA). In many embodiments, the first stage of thetreatment course is configured to apply compression to the periodontalligaments sufficient to generate a biological response in the localenvironment of the tooth. For example, the primer appliance can place aloading on a tooth to provide about 0.02 mm to about 0.3 mm, or about0.2 mm, of movement. The primer appliances may be configured to controlthe strain distribution on the periodontal ligament of each tooth. Insome embodiments, the primer appliances may be configured to applycompression to only a portion of the teeth. For example, the primerappliances may be configured to apply compression to only one or moreselected teeth in each quadrant of the mouth, and a partial compressionmay be sufficient to elicit a biological response in local environmentof the teeth.

The total duration of the primer stage may be tailored for each subjectand/or adjusted during the treatment, such that the primer appliancesare provided for a sufficient length of time to precondition the teeth,in order to begin moving the teeth with movement stages. In order todetermine whether teeth have begun moving, the gingival crevicular fluidof the subject may be tested at intervals, for example at every 2 weeks,to determine the concentration of one or more relevant biochemicalsignals, such as tissue necrosis factor beta (TNF-β), insulin-likegrowth factor (IGF), macrophage colony stimulating factor (M-CSF), andparathyroid hormone (PTH), among others. Alternatively or incombination, the position of the subject's teeth may be tracked visuallythroughout the primer stage to identify movement; for example, thepresence of a separation around the incisal edges may indicate that theteeth have not begun to move and that the primer stage may be extended.Indications by the subject regarding soreness or pain when the appliancehas been removed may indicate when movement has begun.

The subject can provide information and can be instructed to determinewhen the primer stage has been worn for a sufficient amount of time andthe supporting structures of the teeth are conditioned for treatment.When the primer stage appliance is initially placed on the teeth, thesubject may feel a slight discomfort. As the support tissues areconditioned, the slight discomfort diminishes with the primer applianceon the teeth. However, when the primer appliance is removed, the subjectmay feel discomfort. This slight feeling of discomfort with the primerappliance removed and the teeth in an unloaded configuration is anindication that the support structures of the teeth have beenconditioned for teeth movement. The primer stage can be stopped and theintermediate stage started with the next appliance in the series. Thesubjective response of the subject can be combined with one or moreother indicia of completion of the primer stage as described herein.

Optionally, the first stage of the treatment course may comprisedifferent sub-stages, such that each primer appliance (e.g., 311, 312,313) corresponding to a sub-stage is configured to apply a differentdistribution of forces. While in many embodiments the primer stage doesnot comprise a portion of the programmed movement path of a tooth, theforces applied by the primer appliances may cause some movement in oneor more teeth. Such movement may change the direction in whichcompression should be applied in order to achieve the desired finalposition of a tooth. Accordingly, primer appliances may be adjustedduring the primer stage to ensure that the strain distribution placed bythe appliances is appropriate for achieving the desired final position.

The treatment stage 320 may comprise a first treatment appliance 322, asecond treatment appliance 323, and a finishing treatment appliance 327of the final stage of movement, for example. The first treatmentappliance 322 may correspond to the second stage of the treatmentcourse, the second treatment appliance 323 may correspond to the thirdstage of the treatment course, and so forth. Each of the treatmentappliances 322, 323, and 327 may be worn for a second period of time,which may be shorter than the first period of time for which the primerappliances are worn. For example, each of the treatment appliances maybe worn for about 7 to 14 days, or about 10 days. By contrast, intreatment courses without a primer stage, each treatment appliance mayoften be worn for a longer period, usually two weeks.

After the treatment course is completed, the subject may be providedwith a set of orthodontic refinement appliances 330 to further move orreposition the teeth such as to more closely match the final tootharrangement desired or provide an over-correction as described above.Refinement appliances 330 may be provided, for example, if the positionof the teeth at the end of the planned course of treatment deviates fromthe final tooth arrangement desired or if an over-correction of theteeth is appropriate. These orthodontic refinement appliances 330 may bedesigned and manufactured with the process 100 described above.Alternatively or in combination, the refinement appliances may compriseone or more retainers such as Vivera® clear polymeric shell retainerscommercially available from Align Technology of Santa Clara, Calif., forexample. In some embodiments, a retainer includes tooth receivingcavities shaped to maintain the patient's teeth in a desiredarrangement, e.g., the final arrangement resulting from orthodontictreatment. The tooth receiving cavity geometries (e.g., size, shape,position, and/or orientation) of a retainer may be the same as orsimilar to the tooth geometries of the desired tooth arrangement.Accordingly, the retainer may be designed to maintain its shape while atooth tries to return to a former position. In some embodiments, aretainer is used after the teeth have already been repositioned in orderto maintain teeth in their current locations (e.g., at the end of thetreatment plan), while primer appliances are used prior to toothrepositioning in order to prepare teeth for movement away from theircurrent locations (e.g., at the beginning of the treatment plan).Although certain embodiments of the primer appliances described hereinmay not produce tooth movements when worn, such primer appliances canstill apply sufficient forces to the teeth to elicit a biologicalresponse that facilitates repositioning. In some embodiments, the forcesapplied by a retainer, if any, are not sufficient to elicit such abiological response and thus would not prepare the teeth forrepositioning.

FIG. 4 shows an exemplary tooth movement profile 400 of a tooth positionover the course of a treatment. Although a movement profile 400 of asingle tooth is shown, a person of ordinary skill in the art willrecognized that many teeth can be moved similarly with an appliance asdescribed herein. The tooth position can change over time in order tomove the tooth along a path from an initial position to a final positionin accordance with stages of the treatment and the tooth receivingcavities of a series of appliances as described herein. The treatmentprofile comprises an initial primer portion 410 in which the tooth andsupport tissue is primed for movement as described herein. The treatmentprofile comprises an intermediate portion 420, and a finishing portion430. The majority of tooth movement occurs with the intermediate portion420 of the treatment profile. The finishing portion 430 of the treatmentallows the tooth to move to the final target position of the tooth.

The plurality of appliances used to treat the subject can be configuredto move the teeth with the tooth movement profile 400. Each of theplurality of tooth receiving cavities comprises a shape profile toreceive the tooth and a corresponding tooth receiving cavity position.The tooth receiving cavity position corresponds to a position of thetooth at which forces to the tooth are substantially decreased. Thetooth receiving cavity position may correspond to the position to whichthe tooth would move if the tooth had no resistance to mechanical forcesof the appliance, for example. For the primer treatment stages, theposition of the tooth receiving cavity can be within a range from about0.02 to about 1 mm from the initial position of the tooth, for example.The range can be from about 0.04 to about 0.5 mm, for example. Theprimer treatment stage can be provided with a plurality of appliances,or a single appliance provided on the teeth for a greater amount of timethan appliances of the intermediate portion of the treatment. Uponcompletion of the primer portion of the treatment, appliances of theintermediate portion of the treatment are provided. The positions of thetooth receiving cavities of the intermediate portion of the treatmentlead the tooth positions as shown. The tooth receiving cavities of theseries of appliances are arranged to progressively reposition teeth witha plurality of incremental positions. With the finishing portion of thetreatment, the tooth is allowed to move to the position of the toothreceiving cavity. The speed of tooth movement during the finishing stagecan be smaller than the intermediate stage in order to allow the toothto move into the position of the tooth receiving cavity.

The treatments with primer appliances as described herein are wellsuited for use with one or more of many types of subjects. Theappliances are well suited for use with children and adults, forexample. Although the teeth of some children may move more quickly thanthe teeth of some adults, at least some children may have teeth andsupporting structures benefiting from the primer appliances as disclosedherein. Alternatively or in combination, the primer appliances asdescribed herein can be used to treat adults, of age 18 years old ormore, for example. The primer appliance as described herein can beconfigured for placement on the teeth for a suitable amount of time topromote movement of the teeth as described herein, for example at leastabout two weeks.

Each of the treatment portions may comprise tooth movement within anappropriate range as described herein. The amount of movement within arange from about 0.02 to about 0.3 mm during the primer stage can beprovided over a period of time of at least about two weeks, such as fromabout three to about ten weeks, for example. The amount of displacementof the primer stage per week can be within a range from about 0.002 mmper week to about 0.75 mm per week, for example. With the intermediatephase, for each stage the teeth can move within a range from about 0.1mm to about 0.3 mm, for example. The rate of tooth movement can bewithin a range from about 0.05 mm per week to about 0.5 mm per week, forexample. With the finishing stage, the appliance can remain on the teethfor a sufficient amount of time to allow the teeth to move to the finalposition, and the rates can be less than the intermediate stage. Withthe finishing stage the rate of tooth movement can range from about0.002 mm per week to about 0.1 mm per week, for example.

The primer, intermediate and finishing portions of the treatment can beprovided to a patient in one or more of many ways. For example, aplurality of appliances can be provided to the subject, in which eachappliance provides a similar amount of tooth movement in relation toother appliances. The primer stage of treatment may comprise placing thefirst appliance on the teeth for an appropriate amount of time togenerate a biological softening response. The first appliance can beplaced on the teeth for an amount of time to provide a biologicalresponse as described herein, such as softening of the periodontalligament and related changes, for example. The amount of time can rangefrom about 3 weeks to about 12 weeks, for example. The intermediatetreatment can be provided with a plurality of appliances comprising theintermediate treatment stages. The next appliance of the series can beprovided in response to preconditioning of the support tissue with thefirst appliance. The finishing portion of the treatment can be providedwith the last appliance of the series, for example. The last appliancein the series can be placed on the teeth for an amount of time greaterthan each of the appliances of the intermediate portion of thetreatment, for example.

The primer portion of the treatment may comprise placing an applianceconfigured to provide appropriate displacement of the teeth to prime theteeth for movement as described herein. The primer portion of thetreatment may comprise sequentially placing a plurality of primerappliances having the same or similar tooth receiving cavity geometries(e.g., positions and orientations), such as three or more primerappliances having the same or similar cavity geometries. In someembodiments, a plurality of appliances having the same or similar cavitygeometries are used when each appliance is intended to elicit toothmovement to the same tooth arrangement. However, it shall be understoodthat the actual amount of movement achieved by each appliance may vary,e.g., depending on the extent to which the tooth has been prepared forrepositioning at the time when the appliance is worn. For instance, ifthree primer appliances having the same cavity geometry are sequentiallyapplied to reposition a tooth to a targeted location, the firstappliance may elicit the least amount of tooth movement (e.g., 10% ofthe distance to the location), the second appliance may elicit anintermediate amount of tooth movement (e.g., 30% of the distance to thelocation), and the third appliance may elicit the greatest amount oftooth movement (e.g., 60% of the distance to the location).

Although changes to the position of the tooth along one dimension overtime is shown, the tooth can be moved along up to 6 degrees of freedom,up to three translational and up to three rotational degrees of freedom.The incremental positions of the tooth receiving cavity and the positionof the tooth along each degree of freedom can be similarly provided asthe tooth is moved along a treatment vector, for example.

The primer appliances may be provided during the initial weeks of theinitial portion of the movement profile 410 of the treatment, in orderto apply compression to the periodontal ligaments to prepare the teethfor movement along a treatment path. The compressive force can beapplied to each tooth. Alternatively or in combination, the compressiveforce can be applied to some of the teeth of a quadrant and not toothers in a manner that prepares the teeth without the compressive forcefor movement. The biological response to the compressive force can occurwith one or more teeth away from teeth receiving the compressive force.Although the compressive force may be applied to each tooth in aquadrant, this may not be necessary to prepare all of the teeth in aquadrant for movement as the biological response may not be localized tothe teeth receiving the compressive force.

The compression may be applied in many ways to initiate a biologicalresponse. The relatively small amount of tooth movement provided withthe primer stage may not comprise a portion of the planned toothmovement path. Alternatively, the small amount of tooth movementprovided by the primer stage may comprise a portion of the planned toothmovement path. Although the primer stage may or may not result insignificant tooth movement. As shown by tooth movement profile segment412, in the initial weeks 410 of the treatment, there may be little orno tooth movement, corresponding to the amount of time needed for theinitiation of a biological response. Alternatively, as shown by toothmovement profile segment 414, there may be a relatively small amount oftooth movement and resultant change in the position of the tooth in thedirection of the desired final position, since the primer appliances maybe configured to provide compression in a direction favorable forachieving the desired final position of a tooth. Other patterns of toothmovement and change in tooth position may also be possible during theinitial weeks of the primer portion 410. For example, as shown by toothmovement profile segment 416, there may be a small amount of toothmovement without a clearly defined direction, such that the averagechange in tooth position over the initial weeks of the primer portion410 is close to zero or even zero.

Primer appliances can be made such that teeth that do not need to bemoved for treatment do not have their positions changed in the design ofthe primer appliance. This lack of movement at the primer stage canenhance the anchorage of the teeth that are not intended to move.

Following the primer stage, which may comprise the first 3 to 8 weeks ofthe treatment course, the treatment stage may begin, during which thetreatment appliances can be provided to cause tooth movement in theplanned path. In the middle weeks 420 of the treatment, during which thetreatment appliances are provided, the rate of tooth movement and thechange of the position of the tooth can be relatively greater than inthe initial weeks 410. In the later weeks 430 of the treatment, whichmay comprise a separate refinement stage, the rate of tooth movement andthe change of the position of the tooth can be relatively small andreduced from the middle weeks 420. Alternatively or in combination, thelater weeks 430 may comprise a latter portion of the normal treatmentcourse, and may move the teeth at a slower rate than during the middleweeks 420.

The properties of the primer appliances described herein may be variedas desired. In some embodiments, a primer appliance has the same orsubstantially similar properties as a treatment appliance. For instance,a primer appliance may be fabricated from the same or similar materialsas would be used for fabricating a treatment appliance. The stiffness,thickness, hardness, stress relaxation, etc. of a primer appliance maybe the same or similar as that of a treatment appliance. In alternativeembodiments, a primer appliance may have different properties than atreatment appliance, e.g., with respect to stiffness, thickness,hardness, stress relaxation etc., and/or may be fabricated fromdifferent materials than those used for treatment appliances. Theproperties of a primer appliance may vary based on the particular typesof teeth to be primed (e.g., incisors, canines, premolars, molars)and/or the types of tooth movements to be primed (e.g., translation,rotation, tipping, torque, intrusion, extrusion, etc.). Certain types oftooth movements may require a longer priming period, while other typesof tooth movements may be achieved effectively with a shorter primingperiod.

The amount of force and/or torque applied by a primer appliance maydiffer from the amount of force and/or torque applied by a treatmentappliance, e.g., may be more or less. In some embodiments, the teethreceiving cavities of a primer appliance are shaped to apply to applyhigher amounts of force to the teeth compared to a treatment appliance,e.g., in order ensure sufficient induction of the biological response.In alternative embodiments, the teeth receiving cavities of a primerappliance are shaped to apply to apply lower amounts of force to theteeth compared to a treatment appliance, e.g., to reduce patientdiscomfort during the priming stage. Such variations may bepatient-specific, e.g., less force applied to patients with lower paintolerance, geriatric patients, etc. In some embodiments, a primerappliance may be shaped to apply force to teeth without elicitingmovement of the teeth (e.g., using teeth receiving cavities having thesame position and orientation as the corresponding received teeth),while a treatment appliance may be shaped to apply force to teeth thatelicits movement of the teeth (e.g., using teeth receiving cavitieshaving different positions and/or orientations as the correspondingreceived teeth). Teeth receiving cavities having the same position andorientation as the corresponding received teeth can be used to applyforce to the teeth, e.g., due to distortion resulting from the movementof other teeth or forces from the tongue or cheeks with movement beingconstrained by the appliance.

Additionally, although in certain embodiments herein priming is used atthe beginning of an orthodontic treatment, it shall be appreciated thatpriming may also be utilized after treatment has already started, e.g.,to prime teeth that have not yet been moved in a previous treatmentstage. For example, if one or more teeth are not scheduled to be moveduntil partway through the treatment plan, it may be beneficial to applypriming to those teeth prior to repositioning, for the reasons discussedherein. In some embodiments, some tooth receiving cavities of a singleappliance may be used to prime certain teeth for movement, while othertooth receiving cavities of the same appliance may be used to applyforces to reposition other teeth. Thus, the planned movement rate foreach tooth at a particular stage of treatment may vary based on whetheror not the tooth has been previously repositioned during treatmentand/or whether a sufficiently long period of time has elapsed since thetooth was last repositioned. In some embodiments, planning of anorthodontic treatment may involve determining a plurality of teeth to berepositioned from a first arrangement to a second arrangement during theorthodontic treatment, and identifying a first subset of teeth that havealready been repositioned during a previous stage of treatment and asecond subset of teeth that have not yet been repositioned during aprevious stage of treatment. The first subset of teeth may not needpriming to achieve effective movements, while priming of the secondsubset of teeth may be beneficial to prepare those teeth for movement,as described herein. Thus, the treatment planning procedure can involvedetermining a first movement rate for the first subset of the pluralityof teeth appropriate for repositioning and a second movement rate forthe second subset of the plurality of teeth appropriate for priming. Forinstance, the first movement rate can be greater than the secondmovement rate. Orthodontic appliance geometries can be determined toreposition the first and second subsets of teeth according to theirrespective movement rates, thus achieving selective priming of certainteeth while repositioning other teeth.

The appliances described herein can be designed and fabricated with aidof a system including one or more processors. In many embodiments, aprocessor comprises a user input and display for a user to position andorient a plurality of teeth at target positions and orientations foreach stage of a treatment. The processor may comprises instructions toposition teeth receiving cavities of the appliance at positions asdescribed herein in order to provide one or more primer appliances, aplurality of repositioning appliances to reposition teeth with toothmovements as described herein and one or more finishing appliances asdescribed herein. The processor may comprise instructions to manufacturea plurality of appliances with indirect manufacturing comprisingthermoforming or direct manufacturing comprising one or more of 3Dprinting, stereolithography, or fused deposition modeling, for example.

While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. It should be understoodthat various alternatives to the embodiments of the invention describedherein may be employed in practicing the invention. It is intended thatthe following claims define the scope of the invention and that methodsand structures within the scope of these claims and their equivalents becovered thereby.

What is claimed is:
 1. A method for repositioning teeth of a subject,the method comprising: generating an orthodontic treatment planincluding a primer stage and a plurality of treatment stages for a firstselected subset of teeth of the subject, by: generating the plurality oftreatment stages to incrementally move the first selected subset ofteeth along respective tooth movement paths with a first rate ofmovement and not move a second selected subset of teeth, each of theplurality of treatment stages including one of a plurality ofintermediate tooth arrangements in a repositioning of the first selectedsubset of teeth from an initial position towards a target position,wherein an initial intermediate tooth arrangement of the plurality ofintermediate tooth arrangements is in a repositioning direction along arespective tooth movement path; and determining geometries for one ormore primer appliances for a primer stage, wherein the one or moreprimer appliances comprise: (a) a first plurality of teeth receivingcavities shaped to receive the first selected subset of teeth forrepositioning by applying a force or torque to the first selected subsetof teeth sufficient to induce a biological response of supportstructures of the first selected subset of teeth and (b) a secondplurality of teeth receiving cavities shaped to receive and enhance ananchorage of the second selected subset of teeth, wherein the firstselected subset of teeth are moved with a second rate of movement thatis smaller than the first rate of movement; and providing the one ormore primer appliances to be placed on a plurality of teeth of thesubject during the primer stage to prepare the support structures of thefirst selected subset of teeth for repositioning.
 2. The method of claim1, wherein the one or more primer appliances are provided during anintermediate portion of treatment before a movement phase of the firstselected subset of teeth.
 3. The method of claim 1, further comprisingproviding a plurality of appliances of an intermediate portion oftreatment corresponding to the plurality of treatment stages for thefirst selected subset of teeth of the subject, the intermediate portionof the treatment comprising a plurality of repositioning stages.
 4. Themethod of claim 1, further comprising providing one or more finishingappliances for use in a finishing stage of treatment.
 5. The method ofclaim 1, wherein the one or more primer appliances lower resistance of atissue of the subject to the repositioning of the first selected subsetof teeth with a plurality of repositioning appliances.
 6. The method ofclaim 1, further comprising: placing the one or more primer applianceson the plurality of teeth; and placing one or more repositioningappliances on the plurality of teeth, wherein the one or more primerappliances are placed prior to the one or more repositioning appliancesso as to reduce distortion of the one or more repositioning applianceswhen placed on the plurality of teeth.
 7. The method of claim 1, furthercomprising: testing gingival crevicular fluid of the subject anddetermining the concentration of one or more of tissue necrosis factor,insulin-like growth factor, macrophage colony stimulation factors, andparathyroid hormone; and determining that the biological response of thesupport structures has been induced based on a change of concentrationof the one or more of tissue necrosis factor, insulin-like growthfactor, macrophage colony stimulation factors, and parathyroid hormonein the gingival crevicular fluid of the subject.
 8. The method of claim1, wherein the support structures comprise a periodontal ligament. 9.The method of claim 1, wherein the second rate of movement is zero. 10.A method comprising: identifying an orthodontic treatment plan includinga primer stage and a treatment stage, the treatment stage moving a firstselected subset of teeth of a subject and not moving a second selectedsubset of teeth of the subject, the primer stage including a plan toapply a first force on a particular tissue of the first selected subsetof teeth without moving the first selected subset of teeth, and thetreatment stage including a movement plan to move the first selectedsubset of teeth from an initial position towards a target position andnot move the second selected subset of teeth; determining geometries forone or more primer appliances to implement the primer stage, each of theone or more primer appliances comprises: (a) a first plurality of teethreceiving cavities shaped to receive the first selected subset of teethto apply the first force on the particular tissue of the first selectedsubset of the teeth, thereby pre-conditioning the first selected subsetof teeth to be moved in accordance with the movement plan at a firstrate of movement and (b) a second plurality of teeth receiving cavitiesshaped to receive and enhance an anchorage of the second selected subsetof teeth; and providing one or more aligner appliances to implement thetreatment stage, each of the one or more aligner appliances configuredto move the first selected subset of teeth from the initial positiontowards the target position at a second rate of movement that is greaterthan the first rate of movement and not move the second selected subsetof teeth.
 11. The method of claim 10, wherein the particular tissue is aperiodontal ligament of the first selected subset of teeth.
 12. Themethod of claim 10, wherein the first force has a value sufficient toelicit a biological response from the subject to facilitaterepositioning of the first selected subset of teeth during the treatmentstage.
 13. The method of claim 10, wherein the first force comprises acompression force on the particular tissue.
 14. The method of claim 10,wherein the first rate of movement is zero.